(?)=4 means that some thing is a distance of 4 units away from zero on the number line. What could that number(s) be ? why?

Answer 1

4 and -4?

since you said its 4 unit away from the zero, so its either negative or positive

Answer 2

|x-0| = 4

means x is 4 units from 0

4 and -4 is correct for possible values.